Sn-Ni Alloy Flake Plating for Whisker Inhibition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electronic components with Sn plating films, such as laminated ceramic capacitors, face issues with Sn whisker growth that can lead to electrical short circuits, and current methods like forming Sn—Ni alloy grains are inadequate in inhibiting whisker growth under thermal shock conditions.
Innovation Solution
The electronic component features a Ni plating film with a Sn plating film containing Sn—Ni alloy flakes, where the flakes are present up to 50% of the Sn plating film thickness and cover 15% to 60% of the surface area, and an optional intermetallic compound layer of Ni3Sn4 is formed between the Ni and Sn plating films, enhancing whisker inhibition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If Sn plating film is applied to terminals without Pb, then environmental sustainability is improved, but Sn whisker growth occurs causing electrical short circuit
Solution Approach 1:
A Ni plating film is introduced as an intermediary layer between the Sn plating film and the terminal. This Ni layer acts as a mediator that suppresses Sn whisker formation while allowing the Sn layer to maintain its environmental benefits. The Ni-Sn intermetallic compound layer formed at the interface further enhances this whisker-inhibiting effect.
Solution Approach 2:
The invention uses a composite plating structure consisting of multiple layers: Ni plating film, Sn plating film, and Ni-Sn intermetallic compound layer. This composite structure combines the environmental advantages of Pb-free Sn plating with the whisker-inhibiting properties of Ni, creating a multi-functional protective coating system.
2Reliability
If Sn—Ni alloy grains are formed at Sn crystal grain boundaries, then whisker growth is inhibited, but the inhibition is inadequate under thermal shock conditions
Solution Approach 1:
The invention creates local quality differences by forming Ni-Sn intermetallic compound layers specifically at the interface between Ni and Sn plating films, and at Sn crystal grain boundaries. This localized intermetallic compound formation provides enhanced whisker inhibition precisely where needed, particularly under thermal shock conditions that affect grain boundary regions.
Solution Approach 2:
The invention changes the physical and chemical parameters of the plating structure by controlling the formation of Ni-Sn intermetallic compounds with specific compositions (such as Ni3Sn4). By adjusting the thickness, distribution, and composition of these intermetallic layers, the whisker inhibition performance under thermal shock is dramatically improved compared to simple alloy grain formation.
3Reliability
If Ni plating film with Sn plating film containing Sn—Ni alloy flakes is formed, then whisker-inhibiting ability is enhanced, but manufacturing complexity increases
Solution Approach 1:
The Ni plating film is formed first as a base layer, followed by the Sn plating film. The Ni-Sn intermetallic compound layer is then formed in a preliminary heat treatment step before final Sn plating completion. This preliminary formation of intermetallic compounds ensures whisker inhibition is established early in the manufacturing process, simplifying subsequent steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly reduces whisker growth length and improves the whisker-inhibiting ability of the electronic components, maintaining solderability and environmental sustainability by avoiding Pb usage.
Implementation Method 1
an intermetallic compound layer of Ni3Sn4
Implementation Method 2
forming a first Sn plating film on the Ni plating film, forming Sn—Ni alloy flakes in the first Sn plating film
Implementation Method 3
the Sn plating film has Sn—Ni alloy flakes formed therein, the Sn—Ni alloy flakes are present in the range from a surface of the Sn plating film on the Ni plating film to 50% or less of the thickness of the Sn plating film
Data Source
AI summary
An electronic component including an electronic component element with an external electrode, a Ni plating film on the external electrode, and a Sn plating film covering the Ni plating film. The Sn plating film has Sn—Ni alloy flakes therein, the Sn—Ni alloy flakes are present in the range from a surface of the Sn plating film on the Ni plating film to 50% or less of the thickness of the Sn plating film, and when Sn is removed from the Sn plating film to leave only the Sn—Ni alloy flakes, an observed planar view of a region occupied by the Sn—Ni alloy flakes falls within the range from 15% to 60% of the observed planar region.